The National Trauma Data Bank Report for 2004 describes 576,247 hospital admissions for trauma between 1999 and 2004. Of these cases, 109,080 patients were admitted to the intensive care unit (ICU), 100,050 were taken directly to the operating room (OR), and 7878 died. The remaining 332,928 were admitted for general care. For many of these patients (especially for the ICU and OR patients) it was necessary to closely monitor the hematocrit with multiple phlebotomy blood samples within the first few hours. The key to providing optimal care for these challenging patients is for the trauma specialist to provide rapid therapeutic interventions based upon informed decision-making. The clinician's ability to deliver such quality care is based primarily on physical assessment skills, training, and experience, and secondly upon the degree of patient physiologic and hemodynamic data available at the moment of decision-making. There is a clear need for the clinician to have quantitative data to base his or her treatment decision.
The process of frequent phlebotomy consumes valuable emergency staff time and there can be substantial lag-time before results are available. Laboratory techniques have become more accurate and bedside devices have improved turn-around time for in vitro lab analysis, but these improvements have not alleviated the central problem of lack of real time information. The patient's condition may deteriorate within minutes, and reasons for the deterioration can be varied and not always obvious. Survival rates for such patients could be improved if needed data could be provided continuously, allowing better opportunity to act upon the vital information in a more timely manner. Patient monitoring methods have advanced over the decades with the development continuous arterial blood and oximetry pressure monitoring, but there remains no device that delivers other necessary physiologic data on a continuous basis. New Paradigm Concepts (NPC) proposes to remove uncertainty in realm of critical care medicine by developing a point-of-care continuous blood concentration monitor.
In the current practice of critical care medicine, the only patient parameters that are continuously monitored are the vital signs, pulse oximetry, and temperature. Aside from oximetry, the physiologic parameters are available only through phlebotomy sampling and laboratory analysis. The hemodynamic parameters, other than vital signs, are available only with central vascular catheterization in the ICU or the cardiac catheter laboratory. The availability of these continuous physiologic and hemodynamic parameters during patient resuscitation would improve the delivery of appropriate, timely, and cost effective patient care and, thereby, improve outcomes. Such continuous monitoring would also improve the ability of the critical care team to effectively care for multiple patients without the need for numerous and laborious repeat lab tests.
It is an object of the invention to accurately and continuously measure multiple blood parameters within a patient's artery or vein and to precisely trend and display these parameters in a way that is useful for medical clinician interpretation and decision-making.
It is an object of the invention to provide methods and apparatus to accurately and continuously measure blood density (concentration) and hematocrit. For simplicity, hematocrit heretofore will be referred to generally as hematocrit and hemoglobin (H/H).
It is an object of the invention to provide a mathematical relationship between the accuracy of the method of sound speed measurement of H/H and the serum protein content.
It is an object of the invention to provide a method and apparatus to continuously measure and trend pulse pressure (the difference between systolic and diastolic blood pressure).
It is an object of the invention to provide a method and apparatus to continuously and accurately measure and trend blood pressure (systolic, diastolic, mean arterial, and venous).
It is an object of the invention to provide a method and apparatus for blood volume estimation and precise trending.
It is an object of the invention to provide a method and apparatus for continuously and accurately measuring and trending local blood flow velocity.
It is an object of the invention to provide a method and apparatus for mathematical estimation and precise trending and display of an index of local peripheral resistance (LPR) otherwise known as local vascular tone (LVT).
It is an object of the invention to provide a precision temperature probe into the catheter for both sensor calibration and display of the results as a vital sign.
It is an object of the invention to incorporate any or all of the above methods and apparatus into a catheter that can be placed into a peripheral or central vein or artery to measure multiple blood parameters in situ and to display the results for the purposes of clinical interpretation and decision-making.
It is an object of the invention to incorporate into a catheter as many other existing technologies as possible for the purpose of providing continuous information about any blood parameters that are desirable to measure on a frequent basis during the care of a seriously ill or injured patient and to display the results for the purposes of clinical interpretation and decision-making.
Briefly, the present invention consists of a method of ultra-precise measurement of sound speed both intravascularly and non-invasively with the acoustic transducer(s) mounted non-invasively on opposite side of a blood vessel or artery or on an intravascular catheter. The catheter would be similar in length to that used for IV access or arterial line access, and construction would include a port for drawing blood samples or, in the venous application, for administering medications. The present invention provides an apparatus and methods for continuous intravascular measurement of whole blood concentration, blood pressure, and pulse pressure. The intravascular catheter incorporates a sensor to measure whole blood sound velocity, attenuation, backscatter amplitude, and blood flow velocity and also incorporates existing technologies for multiple physiologic measurements of whole blood. Pulse wave velocity and wave intensity are derived mathematically for purposes of estimating degree of local vascular tone. The uniqueness of the invention is in its use for monitoring patients continuously throughout their course of resuscitation and treatment in its novel ultrasound methods for accurate measurement of H/H, pulse pressure, and blood pressure, and in its incorporation of other technologies to provide a plethora of physiologic and hemodynamic data heretofore obtained only by complex invasive means.
Additional features and advantages of the gripper assembly will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrated embodiment exemplifying the best mode of carrying out the gripper assembly as presently perceived.